# set terminal png transparent nocrop enhanced font arial 8 size 420,320 
# set output 'pm3d.2.png'
set border 4095 lt -1 lw 1.000
set samples 25, 25
set isosamples 20, 20
set ticslevel 0
set title "pm3d at s (surface) / ticslevel 0" 0.000000,0.000000  font ""
set xlabel "x" 0.000000,0.000000  font ""
set xrange [ -15.0000 : 15.0000 ] noreverse nowriteback
set ylabel "y" 0.000000,0.000000  font ""
set yrange [ -15.0000 : 15.0000 ] noreverse nowriteback
set zrange [ -0.250000 : 1.00000 ] noreverse nowriteback
set cblabel "colour gradient" 0.000000,0.000000  font ""
set pm3d at s
splot sin(sqrt(x**2+y**2))/sqrt(x**2+y**2)